Homebrew PCBs

Most chemical reactions speed up when heat is applied. Chemistry 101.

Nearly all of the commercial/industrial
PCB etch tanks have heaters regardless of the etchant being used. 
Generally for hobby
use, heating the etchant to a few degrees above ambient increases the 
process significantly.
In the summer time here in southern Arizona when the ambient is often 
over 105 degrees F,
the heat gun gimmick becomes unnecessary.

I usually do my etching out on the back patio in free air to avoid 
contamination of the
household environment. I wave a heat gun over the surface of the etchant 
for a few
seconds to slightly raise the temperature. I use a glass (Pyrex) baking 
dish. With
hydrogen peroxide and muriatic acid, etch time is usually less than ten 
minutes,
rocking the dish constantly.
I neutralize the etchant with a copious amount of baking soda. After 
neutralization, I mix about 16 oz of etchant in a gallon tap water to 
dilute it  and pour it down the washtub drain in the garage. I never 
have any of this stuff actually in my living quarters.

HTH

Roland F. Harriston



Stefan Trethan wrote:
> On Mon, 20 Nov 2006 16:32:10 +0100, Adi Linden <adiy@...> wrote:
>
>   
>> There is no way I'll be 'cooking' FeCl in anything that will ever see  
>> food
>> again. So a dedicted microwave would be the only way to heat etchant in
>> small quantities.
>> The other item that has become pretty obvious that in my environment  
>> doing
>> board in the kitchen sink just doesn't work too well. No matter how
>> careful, there is always the possibility that something spills. I'd  
>> rather
>> not have any poison near my food preparing areas, period.
>> Looking at building an etch tank, from a cost perspective it is equal to
>> getting a small microwave. Having etched board in a ammonium persulfate
>> bubble bath many moons ago, I know it does work well. I never tried the
>> sponge method yet, but read it is supposed to be excellent. Problem is, I
>> don't have the confidence to play with FeCl in my stainless steel kitchen
>> sink...
>> Adi
>>     
>
>
> Nobody says microwave heating is required, or even preferred, for FeCl  
> etching.
> You can use just about any heat source and rig something up.
> Also, you do not need to heat the ferric chloride if you don't want. You  
> can use larger vessel on the outside in which you fill hot water (from the  
> kitchen).
> Aquarium heaters are often used, but i expect that electric foil heaters  
> would work stuck to the side of a tank.
> A few days ago i got a "get a free heater" leaflet from Minco,  
> www.minco.com/freeheater. The promo code is H1016FH (it is bulk-printed  
> with the leaflets so not an individual code). I think there were a few  
> that would work, and free too!
>
> ST
>
>
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>
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